Endoscopic surgical instruments are often preferred over traditional open surgical devices since the use of a natural orifice tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a working end of a tool at a desired surgical site, as well as articulation and/or actuation of various of the working end of the device upon arrival at the treatment site. These tools can be used to engage and/or treat tissue in a number of ways to achieve a diagnostic or therapeutic effect.
Endoscopic surgery requires that the shaft of the device be flexible while still allowing the working end to be articulated to angularly orient the working end relative to the tissue, and to be actuated to treat tissue. The controls for articulating and/or actuating a working end of an endoscopic device tend to be complicated by the elongate nature of the flexible shaft. Generally, the control motions are all transferred through the shaft as longitudinal translations, which can interfere with the flexibility of the shaft. In particular, as the shaft flexes during passage through a tortuous lumen, tension is applied to the control mechanism. This in turn can restrain the flexibility or cause undesired flexing of the shaft. Additionally, control of the working end of such devices is further complicated when utilizing control wires that do not pass through the center of the flexible shaft because the wires become longer or shorter as the shaft is flexed.
Accordingly, there remains a need for improved devices and methods for actuating a working end of a flexible endoscopic surgical device.